I have two tables, Schedule and UserSchedule. UserSchedule has columns schedule_id and user_id. What I want to do is something like this select s from schedule s join user_schedule us on s.id = us.schedule_id where us.user_id = ?. This works as intended if I run this query directly to db.
Schedule entity has userSchedule and all other necessary info
#Setter
#Getter
#JoinColumn(name = "id", referencedColumnName = "schedule_id")
#OneToOne
private UserSchedule userSchedule;
What's so weird is that I have #Query("select s from Schedule s join s.userSchedule") , and hibernate creates
select schedule0_.id as id1_10_, schedule0_.created_at as created_2_10_, schedule0_.end_date as end_date3_10_, schedule0_.end_time as end_time4_10_, schedule0_.frequency as frequenc5_10_, schedule0_.frequency_val as frequenc6_10_, schedule0_.is_active as is_activ7_10_, schedule0_.start_date as start_da8_10_, schedule0_.start_time as start_ti9_10_, schedule0_.updated_at as updated10_10_, schedule0_.description as descrip11_10_, schedule0_.lat as lat12_10_, schedule0_.lon as lon13_10_, schedule0_.project_id as project15_10_, schedule0_.title as title14_10_, (select v.status from voucher v where v.schedule_id = schedule0_.id) as formula1_ from schedule schedule0_ inner join user_schedule userschedu1_ on schedule0_.id=userschedu1_.id limit ?
The last part of the query on schedule0_.id=userschedu1_.id which should be I think on schedule0_.id=userschedu1_.schedule_id. Why tho? I can't seem to find any error.
Related
I have an Entity with a ManyToOne Relationship to the Primary Key of another entity. When I create a query that references this Foreign Key eclipseLink always creates a join instead of simply accessing the Foreign Key.
I have created a highly simplified example to show my issue:
#Entity
public class House {
#Id
#Column(name = "H_ID")
private long id;
#Column(name = "NAME")
private String name;
#ManyToOne
#JoinColumn(name = "G_ID")
private Garage garage;
}
#Entity
public class Garage{
#Id
#Column(name = "G_ID")
private long id;
#Column(name = "SPACE")
private Integer space;
}
I created a query that should return all houses that either have no garage or have a garage with G_ID = 0 using the CriteriaBuilder.
CriteriaBuilder cb = entityManager.getCriteriaBuilder();
CriteriaQuery<House> query = cb.createQuery(House.class);
Root<House> houseRoot = query.from(House.class);
Path<Long> garageId = houseRoot.get(House_.garage).get(Garage_.id);
query.where(cb.or(cb.equal(garageId , 0), cb.isNull(garageId)));
TypedQuery<House> typedQuery = entityManager.createQuery(query);
List<House> houses = typedQuery.getResultList();
The generated query is:
SELECT h.NAME, h.G_ID FROM HOUSE h, GARAGE g WHERE (((h.G_ID= 0) OR (g.G_ID IS NULL)) AND (g.G_ID = h.G_ID));
I don't understand why
The or condition first references table HOUSE and then GARAGE (instead of HOUSE)
The join is created in the first place.
The correct query should look like this in my understanding:
SELECT h.NAME, h.G_ID FROM HOUSE h WHERE (((h.G_ID= 0) OR (h.G_ID IS NULL));
Or if a join is made it should take into account that the ManyToOne relationship is nullable and therefore do a LEFT OUTER JOIN.
SELECT h.NAME, h.G_ID FROM HOUSE h LEFT OUTER JOIN GARAGE g ON (h.G_ID = g.G_ID ) WHERE (h.G_ID = 0) OR (g.G_ID IS NULL);
(Note both these queries would work correctly in my more complicated setup. I also get the same error when only wanting to retrieve all houses that have no garage.)
How can I achieve this (while still using the CriteriaBuilder and ideally not having to change the DB Model)?
(Please let me know any additional information that might be required, I'm very new to this topic and came across this issue while migrating an existing application.)
-- edit --
I have found a solution to my problem that will result in slightly different behaviour (but in my application that part of the code I had to migrate didn't make much sense in the first place). Instead of using
Path<Long> garageId = houseRoot.get(House_.garage).get(Garage_.id);
I use
Path<Garage> garage = houseRoot.get(House_.garage);
And then as expected table Garage isn't joined anymore. (I assume the code previously must have been some kind of hack to get the desired behaviour from openJPA)
I don't understand why
The or condition first references table HOUSE and then GARAGE (instead of HOUSE)
I believe this is implementation specific; in any case, it shouldn't have any bearing on the results.
The join is created in the first place.
By saying Path<Long> garageId = houseRoot.get(House_.garage).get(Garage_.id) you're basically telling EclipseLink: 'join Garage to House, we're gonna need it'. That you then access Garage_.id (and not, for example, Garage_.space) is inconsequential.
If you don't want the join, simply map the G_ID column one more time as a simple property: #Column(name = "G_ID", insertable = false, updatable = false) private Long garageId. Then refer to House_.garageId in your query.
Or if a join is made it should take into account that the ManyToOne relationship is nullable and therefore do a LEFT OUTER JOIN.
Path.get(...) always defaults to an INNER JOIN. If you want a different join type, use Root.join(..., JoinType.LEFT), i. e. houseRoot.join(House_.garage, JoinType.LEFT).get(Garage_.id).
One solution that results in the same behaviour is:
CriteriaBuilder cb = entityManager.getCriteriaBuilder();
CriteriaQuery<House> query = cb.createQuery(House.class);
Root<House> houseRoot = query.from(House.class);
Path<Garage> garage = houseRoot.get(House_.garage);
Path<Long> garageId = garage.get(Garage_.id);
query.where(cb.or(cb.equal(garageId , 0), cb.isNull(garage)));
TypedQuery<House> typedQuery = entityManager.createQuery(query);
List<House> houses = typedQuery.getResultList();
This results in the following SQL:
SELECT H_ID, NAME, G_ID FROM HOUSE WHERE ((G_ID = 0) OR (G_ID IS NULL));
QueryDSL is not working properly with JPA for left join.
I am using queryDSL version 4.2.1 and mapping the response directly to javax.persistence entity.
For Left join/Right join, the joining condition it's not working. It fetches every entity disregarding the joining condition(here it's name = "testName") when entity1.getEntity2() is being called.
Is there any other way applicable for this case to map the result after JOIN tables ?
JPAQuery<Entity1> query = new JPAQuery<>(entityManager);
query.from(table1);
query.leftJoin(table2).on(table2.id.eq(table1.id).and(table2.name.eq("testName"));
List<Entity1> list = query.fetch();
#Entity
public class Entity1{
private Integer id;
#OneToMany(mappedBy = "entity1", fetch = FetchType.LAZY)
private List<Entity2> entity2;
}
An left or right join is an outer join.
So if you use left join all records from the left (in your case table1) will be selected.
If you only want records from table1 if there are corresponding records on table2 you have to use innerJoin.
JPAQuery<Entity1> query = new JPAQuery<>(entityManager);
query.from(table1);
query.innerJoin(table2).on(table2.id.eq(table1.id).and(table2.name.eq("testName"));
List<Entity1> list = query.fetch();
Read more about the join types here:
https://www.diffen.com/difference/Inner_Join_vs_Outer_Join
I use JPA 2.0 criteria builder. I need get data from one table and sort them by column from other. This tables have relations OneToMany:
class Club{
#OneToMany(mappedBy = "club")
private List<Address> addresses;
...
}
class Address{
#JoinColumn(name = "club_id", referencedColumnName = "id")
#ManyToOne(fetch = FetchType.LAZY)
private Club club;
#Column(name = "type")
private Long type;
#Column(name = "full_address")
private String full_address;
...
}
May be several address of some type but I need only one row of this specific address.
I write native queries with subquery, but it's has problem because subquery doesn't use in order clause and in select clause in JPA 2.0.
select c.full_name from club c
ORDER BY (select a.full_address from address a WHERE c.id= a.club_id and a.type=1 LIMIT 1)
select c.full_name, (select a.full_address from address a WHERE a.type=1 AND c.id=a.club_id LIMIT 1) as full_address FROM club c
ORDER BY fullAddress;
How I can replace native order by clause on JPA equivalent?
Thanks!
This native query also resolve problem and it can replace by JPA query
select c.full_name, min(a.full_address) FROM club c LEFT JOIN address a on c.id = a.club_id
where a.id is null or a.type=1 or not exists(SELECT 1 from address aSub WHERE aSub .club_id=c.id AND aSub.type=1)
GROUP BY c.id, c.full_name ORDER BY min(a.full_address);
JPA equivalent
CriteriaBuilder builder = em.getCriteriaBuilder();
CriteriaQuery<ClubItem> query = builder.createQuery(ClubItem.class);
Root<Club> root = query.from(Club.class);
Join<Club, Address> addressJoin = root.join(Club_.address, JoinType.LEFT);
query.select(builder.construct(ClubItem.class, root.get(Club_.id), root.get(Club_.fullName), builder.function("min", String.class, addressJoin.get(Address_.fullAddress))));
Subquery<Address> subquery = query.subquery(Address.class);
Root<Address> addressRoot = subquery.from(Address.class);
subquery.select(addressRoot);
subquery.where(
builder.and(
builder.equal(addressRoot.get(Address_.type), 1),
builder.equal(addressRoot.get(Address_.clubId), root.get(Club_.id))));
query.where(builder.or(builder.isNull(addressJoin), builder.equal(addressJoin.get(Address_.type), builder.literal(new Long(1))),
builder.not(builder.exists(subquery))));
query.groupBy(root.get(Club_.id), root.get(Club_.fullName))
Order order = builder.asc(builder.function("min", String.class, addressJoin.get(Address_.fullAddress)));
query.orderBy(order);
TypedQuery<ClubItem> contentQuery = em.createQuery(query);
It's not terribly elegant, but it gets the job done...
Make your "Club" class implement Comparable. Put the order-by logic into the Comparable. Then use Collections.sort(unsortedList) to get the list into sorted form. There's also a Collections.sort(unsortedList, Comparable) method which could be useful, especially if you are doing a bunch of similar methods that just vary on order-by.
I have two JPA entities
public class Job {
#ManyToOne
#JoinColumn(name = "service")
public Service service;
#Column(name = "queue_time")
public Long queueTime;
#Column(name = "run_time")
public Long runTime;
}
public class Service {
#Id
#Column(name = "id")
public Long id;
#Column(name = "name")
public String name;
#Column(name = "host")
public String host;
}
Now I want to do some aggregation queries with JPQL:
SELECT job.service.id, AVG(job.queueTime), AVG(job.runTime) FROM Job job GROUP BY job.service.id
The resulting SQL query (I'm using a MySQL database) looks like this:
SELECT t0.id, AVG(t1.queueTime), AVG(t1.runTime) FROM Service t0, Job t1 WHERE (t0.service = t1.id) GROUP BY t0.id
As you can see, JPA translates my JPQL query to a SQL query with a join. This however slows down the query dramatically. The following SQL query executes ~6 time faster and returns the exact same result set:
SELECT t1.service, AVG(t1.queueTime), AVG(t1.runTime) FROM Job t1 GROUP BY t1.service
If I change the JPQL query to
SELECT job.service, AVG(job.queueTime), AVG(job.runTime) FROM Job job GROUP BY job.service
the resulting SQL query looks like this:
SELECT t0.id, t0.name, t0.host AVG(t1.queueTime), AVG(t1.runTime) FROM Service t0, Job t1 WHERE (t0.service = t1.id) GROUP BY t0.id, t0.name, t0.host
Is there a way to write the JPQL which only queries the job table without making a join to the service table?
This question solved the issue for me: How can I retrieve the foreign key from a JPA ManyToOne mapping without hitting the target table?
I took the second solution (b) Use read-only fields for the FKs)
I have a problem in JPQL cascade query with eclipselink2.5
please see code
Entity code
public class Category{
...
#JoinColumn(name = "parent_category", referencedColumnName = "id")
#ManyToOne(cascade = CascadeType.REFRESH, fetch = FetchType.EAGER,optional = true)
private Category parentCategory;
...
}
JPQL code
String jpql = "select o from Category o order by o.parentCategory.sort ASC";
problem
the problem is this JPQL return list does not include 'o' if 'o.parentCategory' is null.
please see this table http://i.stack.imgur.com/xsXvk.jpg
the return list only rows id is 2,3,4 .
because the column parent_category is null, I lost rows 1,5,6
the correct result should be return all rows
Looking forward to your help！
Using o.parentCategory.sort in the order by clause forces an inner join which filters nulls. If you want nulls included, you will need to use an explicit outer join in the query:
"select o from Category o outer join o.parentCategory parentCategory order by parentCategory.sort ASC"